This invention relates to cooling systems for electric circuit chips and, more particularly, to a manifold having flexible connectors for mating with a plurality of individual chip heat exchangers for the cooling of electric circuits.
Electric circuits are fabricated frequently in the form of chips. Complex electronic systems are constructed of many such chips which are disposed on a common substrate, such an arrangement of the chips being referred to as a module. A module may have as many as one hundred or more chips. A set of the modules may be electrically interconnected to provide still larger systems.
A particular concern in the construction of the modular electronic systems is the production of heat by the electric circuits. Because of the many circuits, the heat is considerable. The heat must be removed to prevent excessive heating and destruction of the circuits.
High power chips can now be cooled by use of forced-convection silicon heat exchangers which are thermally attached to respective ones of the chips, as is described in the following articles: (1) D. B. Tuckerman and R. F. W. Pease, "High Performance Heat Sinking for VLSI", IEEE Electron Device Letters EDL-2, Page 126 (1981); and (2) A. Zingher and P. Gruber, "Chip Cooling for Very High Power Density Electronic Packaging", ITL Conference, Boca Raton, Fla. (1983). A source of cooled liquid such as water is connected between input and output ports of the heat exchangers to pass the water through the heat exchangers for removal of heat from the circuit chips. An array of the heat exchangers connected to respective ones of the chips is an effective means for maintaining proper operating temperature for an entire module of electric circuits. All of the heat exchangers are to be connected to the source of cooling liquid for removal of heat from the module.
A problem arises in the connection of a source of cooling water to many heat exchangers mounted on the chips of a circuit module because of the dense packaging of the chips. The chips and the heat exchangers mounted thereon may be positioned in two dimensions with a pitch of less than a centimeter, and each heat exchanger has two ports (input and output) which are to be connected to the water source. A particular aspect of the problem is manifested in the maintenance of tolerances among positions of the ports to allow for an interfacing with a suitable connection device.
A further aspect of the problem is the necessity for stress relief because of the specific materials employed in the construction of the electric circuits. For example, the substrate upon which the chips are mounted may be fabricated of ceramic, and semiconductor circuitry within the chips may be fabricated of silicon. Both the ceramic and the silicon are rigid materials which might introduce excessive stress to soft metallic ball contacts located between the chips and the substrate for making electrical connection between circuits of the chips and electrical conductors located in the substrate. Therefore, there is a need for mechanically decoupling the source of cooling water from the heat exchangers to prevent a buildup of any additional stresses which might be introduced by the water source.